Teardown Tuesday: Leap Motion Controller

The Leap Motion Controller is a device capable of tracking all ten fingers to provide advanced gesture tracking for computer control and augmented reality environments. In this teardown, we look at the circuitry inside the controller.

Construction and Disassembly

Construction

The Leap Motion Controller electronics are populated on two circuit boards. Those two circuit boards sit in a black plastic carrier that is secured to the aluminum housing from below with five screws. The case is topped with an IR filter that is glued in place inside a bezel in the aluminum housing.

Disassembly

Begin by removing the soft plastic at the base of the device to reveal five screws that hold the circuit board carrier securely inside the case. Remove those five screws.

Use a heat gun to loosen the glue that holds the plastic lens in place at the top of the device. While still warm, use a punch to push the plastic circuit board carrier by way of the screw holes in the aluminum base. The pressure you apply will push the carrier against the IR lens, eventually dislodging it from the aluminum bezel. Continue applying pressure to dislodge the carrier board from the aluminum case.

There are two circuit boards that hold all the circuitry. The marking "SUNNY" indicates that they're made by Sunny Optical, a Chinese company that produces a wide variety of high-end optical equipment and optical devices. Unfortunately, without better markings, I cannot guess which IR-emitters and IR-camera boards they used.

There is not enough microcontroller circuitry inside the Leap Motion Controller to process the images inside the device. Camera (indicated in orange on the image below) images must be sent by the high-speed USB interface (red) to the computer for processing.

CYUSB3014-BZXI (Red)

According to the datasheet, this high-speed USB controller has a 200-MHZ 32-bit ARM926EJ CPU and is capable of 5 Gbps data transfer. It can communicate with other devices with a 100-MHz General Programmable Interface (see GPIF II designer) and it has support for SPI, UART, I²C, and I²S.

Most of the circuitry on the circuit boards operates at 3.3V. However, the circuit board also has a coil and capacitor present to create a voltage boost converter. This 35V P-Channel MOSFET is likely part of that circuit and present to regulate the power supplied to the IR emitters.

SFH4714AS* (Purple)

I cannot positively identify the IR emitter present on the circuit boards, so I chose one based on similar appearance. The high-output IR emitters illuminate the immediate vicinity of the Leap Motion Controller. These provide the light that reflects off of your hands back into the camera modules.

Conclusion

The Leap Motion Controller is an advanced piece of engineering that captures two-dimensional images and uses them to create a model of three-dimensional space in the immediate vicinity of the controller. The circuitry is designed to illuminate hands, capture images of those hands, and send the images to the computer for processing.

A look at the math used to determine finger movement in the patent application helps explain why the designers chose to send the images from the cameras to the computer for processing. A large amount of memory and a fast processor are required to solve the equations necessary to determine the position of all ten fingers in three-dimensional space. To put those devices inside the controller would increase the bulk, material cost, and power consumption of the device—three aspects to be considered when designing any device, particularly a wearable.